The motive for the attack is unclear but police are investigating whether it was a hate crime.
Several Israelis have been stabbed by Palestinians in Israel and the occupied West Bank in recent weeks.
Mr Graff was attacked outside a kosher restaurant. Police are still searching for the assailant.
A statement from Milan`s Jewish community said it hoped the attack was an isolated incident.
"We have never had problems in Milan. We don`t think this was a personal affair - there is nothing to suggest that," the community`s co-president Milo Hasbani told reporters, according to Reuters.
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